The invention relates to link management, and more particularly, to methods and apparatuses for link management in a scatternet.
Bluetooth is a wireless personal area network (WPAN) standard for short-range transmission of digital voice and data. Bluetooth is widely used for hands-free mobile phone operations, such as connections between wireless headsets and Bluetooth-enabled automobiles that turn the car's audio system into a speakerphone. It can also be used to transfer data between mobile phones and computers. With the support of point-to-point and multipoint applications, Bluetooth provides up to 720 Kbps of data transfer within a range of 10 meters and up to 100 meters with a power amplifier. Digital voice and data are transmitted in the unlicensed 2.4 GHz band. Bluetooth technology uses a frequency hopping spread spectrum technique that changes its signal 800 times per second.
A piconet is an ad-hoc network of Bluetooth devices, similar with star-topology, to allow one master device to interconnect with up to seven active slave devices. The master device is operated as the central node and the slave devices are operated as dependent nodes. The timing of the piconet is controlled by the master device, and the slave devices synchronize their clocks with that of the master device. A scatternet is a set of piconets. When a slave device simultaneously participates in two or more piconets and the timings of the participating piconets are not synchronized, the slave device requires to switch to each piconet so as to maintain ACL (asynchronous connection oriented) link in each piconet. An ACL link associated with a piconet, however, may be automatically disconnected due to a certain number of polling timeouts. Thus, methods and apparatuses for link management in a scatternet are required to avoid exceptional disconnections.